Conventionally, methods using so-called an electronic shutter function in which an electric charge accumulation time period in a solid-state imaging device is controlled by discharging electric charges accumulated in the solid-state imaging device through a photoelectric conversion (for example, see Patent Literature (PTL) 1 to 3). Hereinafter, a conventional image-capturing apparatus having the electronic shutter function will be described.
FIG. 14 is an exemplary function block diagram showing a configuration of a camcorder which is the image-capturing apparatus.
The camcorder includes: a lens 302 and an aperture/mechanical shutter 303 positioned at the light receiving side of a solid-state imaging device 301; an analog signal processing unit 304 which receives image-captured data generated in the solid-state imaging device 301 which has received light, and performs correlated double sampling and A/D conversion that is conversion from an analog signal to a digital signal; a digital signal processing unit 305 which receives the analog processed digital image-captured data (image signal) and generates image-captured image data through signal processing such as RGB/YC conversion; a graphic I/F 306 for displaying the image-captured image data digitally processed in the digital signal processing unit 305 on a monitor; a display 307 which displays the image-captured image data; a compression signal processing unit 308 which compresses the digitally processed image-captured image data to image-captured image data in JPEG format and the like; a recording medium 309 on which the compressed image-captured image data is recorded; and a system controlling unit 310 which outputs/inputs output data from the analog signal processing unit 304 and the digital signal processing unit 305, a control signal, and others.
The system controlling unit 310 controls, according to the image-captured image data including information about an amount of exposure and others provided to the system controlling unit 310, an electronic shutter driving unit (TG) 311 for controlling an operation of an electronic shutter in the solid-state imaging device 301, an exposure controlling driver 312 for controlling the aperture/mechanical shutter 303, and a lens driver 313 for controlling the lens.
FIG. 15 is a flowchart showing a procedure of representative exposure compensation used in the camcorder configured as above.
The solid-state imaging device 301 receives incident light to generate an image signal, and the generated image signal is processed in the analog signal processing unit 304 and the digital signal processing unit 305, to be image-captured image data. The image-captured image data is provided to the system controlling unit 310, rough exposure compensation is performed by controlling the aperture/mechanical shutter 303 according to the provided image-captured image data (Step S11), and then exposure compensation is performed by adjusting electronic shutter speed (an electric charge accumulation time period) of the electronic shutter driving unit 311 (Step S12).
Here, there may be a case where the aperture/mechanical shutter 303 is not installed in the camcorder to avoid an increase in cost, so that the exposure compensation in Step S11 shown in FIG. 15 is not performed but exposure compensation is performed only with an adjustment of the electronic shutter speed in Step S12.